Gonorrhea, a common sexually-transmitted disease (STD), is usually treated with antibiotics,

IBtimes reports: The man reportedly caught the rare STD strain while traveling Southeast Asia and was diagnosed during his visit to a health clinic earlier this year, the report said.

"We are investigating a case who has gonorrhea which was acquired abroad and is very resistant to the recommended first-line treatment," said Dr. Gwenda Hughes, Consultant Scientist and Head of Sexually Transmitted Infection (STI) Section at PHE, according to BBC News.

Gonorrhea, usually transmitted via unprotected sexual intercourse, is typically treated with a combination of antibiotics (azithromycin and ceftriaxone). This is the first strain resistant to both drugs, according to the PHE.

"This is the first time a case has displayed such high-level resistance to both of these drugs and to most other commonly used antibiotics," said Hughes. "We are following up this case to ensure that the infection was effectively treated with other options and the risk of any onward transmission is minimized."

According to a report released in July by the World Health Organization, antibiotic resistance has made gonorrhea a more difficult disease to treat.

"The bacteria that cause gonorrhea are particularly smart. Every time we use a new class of antibiotics to treat the infection, the bacteria evolve to resist them," Dr. Teodora Wi said in a statement released by the WHO.

"These cases may just be the tip of the iceberg since systems to diagnose and report untreatable infections are lacking in lower-income countries where gonorrhea is actually more common."

Dr. Olwen Williams, the president of the British Association for Sexual Health and HIV, told the BBC that the issue could worsen due to health clinic closures and budget cuts in sexual health service programs.

Gonorrhea, caused by the Neisseria gonorrhoeae virus, leads to symptoms including a burning sensation during urination and unusual discharge from the genitals, according to the Centers for Disease Control and Prevention. If left untreated, it could result in infertility. Experts recommend condom use with casual and committed partners.